Quantifying the Impact of Auditory Deafferentation on Speech Perception

Area of Science:

• Auditory Neuroscience
• Speech Perception
• Computational Auditory Modeling

Background:

• Research indicates morphological changes in the auditory periphery may cause hearing difficulties in noise despite normal hearing thresholds in quiet.
• Cochlear synaptopathy (inner ear nerve damage) may lead to auditory nerve deafferentation and impaired signal transmission to the brain.

Purpose of the Study:

• To quantify the perceptual consequences of auditory deafferentation in humans using a physiologically inspired encoding-decoding model.
• To assess how varying degrees of deafferentation impact speech perception in quiet and noisy conditions.

Main Methods:

• Developed an encoding-decoding model simulating auditory periphery processing and auditory nerve activity.
• Trained the decoding stage to regenerate speech stimuli from simulated neural data.
• Measured speech perception thresholds in quiet and noise as a function of modeled deafferentation levels.

Main Results:

• Speech perception thresholds significantly worsened with deafferentation exceeding 90%.
• The negative impact on speech perception was more pronounced in noisy backgrounds compared to quiet.
• The model successfully replicated degraded speech perception in noise with preserved perception in quiet.

Conclusions:

• The encoding-decoding model effectively quantifies the perceptual effects of auditory deafferentation.
• This model may serve as a tool for evaluating the degree of auditory deafferentation in individuals.
• Findings highlight the critical role of intact auditory nerve function for robust speech understanding, particularly in challenging listening situations.